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New Planet A new dwarf planet has been discovered in the dark outer reaches of the solar system, far beyond Pluto, according to astronomers.

The 450-kilometre-wide object named 2012-VP113, was found orbiting about 80 times further out from the Sun than Earth's orbit.

The find, reported in the journal Nature, is the first object detected in a remote frozen region of space called the inner Oort Cloud, since the discovery of the dwarf planet Sedna, 10 years ago.

The discovery will help astronomers better understand how the Oort Cloud formed, its relationship to our solar system, and the solar system's evolution, according to one of the object's discoverers, Scott Sheppard, of the Carnegie Institution for Science in Washington DC.

"Until we found 2012-VP113, the 1000-kilometre-wide Sedna was the only known object in this region, and we were wondering if that was a unique body or just the tip of the iceberg of a bunch of objects out there," says Sheppard.

Distant and remote

The solar system can be broadly divided into three regions, the rocky terrestrial planets and asteroids, the giant gas planets, and the icy Kuiper Belt objects such as Pluto.

Beyond this is the Oort Cloud, which extends into interstellar space.

Astronomers use a system called Astronomical Units or AU, to measure distances across the solar system, where 1AU is the average distance between the Earth and Sun, approximately 149.6 million kilometres.

Sheppard, together with co-author Dr Chad Trujillo, of the Gemini Observatory in Hawaii, calculated 2012-VP113's orbit brings it no closer to the Sun than Sedna's orbit, which at 76AU, is almost twice as far away as Pluto.

"That's the closest it ever comes, it's a very elongated orbit which goes all the way out to 450AU, which is very distant," says Sheppard.

"We know that it's pinkish red in colour, which suggests that it's probably dominated by water ice and frozen methane on its surface."

Unexplained

Sheppard and Trujillo are now trying to determine why objects like 2012-VP113 and Sedna are out there.

They don't believe these bodies formed where they are because their orbits aren't circular, and there's not much material out there.

"These objects are too distant from the giant planets to have been gravitationally tossed out there from the inner solar system," says Sheppard.

"They have very elongated and eccentric orbits, yet there's nothing that interacts with them, and they're too close to the Sun to have interacted with the galactic tide [the gravitational pull from other nearby stars], so it's a very strange situation."

According to Sheppard, there's nothing in our present solar system to explain their existence.

"So something was different in our distant past, and that tells us these objects were moved to their present location during the formation of the solar system, when conditions were vastly different to what they are now," says Sheppard.

Sheppard suggests 2012-VP113 and Sedna are members of a yet-to-be-discovered large population of inner Oort cloud objects, that could number in the thousands.

The authors have 10 additional inner Oort Cloud objects they are currently targeting.

"We've only covered a small area of the Oort Cloud, and if we covered the entire sky, we could find more than 1000 objects, more than a 1000 kilometres in size ... some of them could easily be Mars or Earth sized," says Sheppard.